Insulation divider for refrigerator cabinet

ABSTRACT

A refrigerator cabinet having a transverse partition for dividing the cabinet into an upper freezer compartment and a lower food storage compartment. The partition includes a composite insulation separator and drain trough structure in the form of a molded moisture impervious sealed plastic separator shell completely filled with unfused pre-expanded polystyrene contacting beads, each of the beads being substantially spherical in shape and having a diameter of the order of 0.060 to 0.100 inches whereby convection heat transfer between the upper and lower shell walls is obviated.

imited States Patent [1 1 [11] 3,868,829 Mann et al. Mar. 4, 1975 1INSULATION DIVIDER FOR 3.766.749 /1973 Linesay 62/289 REFRIGERATORCABINET 3.774.408 ll/l973 Pruehs 62/285 [75] Inventors: Leonard J. Mann,Kettering; John v Primary E.\ammer-Wlllram J. Wye Kemper Beubrook bothof Ohio Attorney, Agent, or Firm-Edward P. Barthel [73] Assignee:General Motors Corporation,

Detroit, Mich. [57] ABSTRACT [22] Flled: 1973 A refrigerator cabinethaving a transverse partition for [21] Appl. No.: 420,528 dividing thecabinet into an upper freezer compartment and a lower food storagecompartment. The partition includes a composite insulation separator and2% 62/285 i i drain trough structure in the form of a molded moisi 288789 ture impervious sealed plastic separator shell com- 1 0 can pletelyfilled with unfused pre-expanded polystyrene contacting beads, each ofthe beads being substantially [56] References Cited spherical in shapeand having a diameter of the order UNITED STATES PATENTS of 0.060 to0.100 inches whereby convection heat 3.280.583 10/1966 Jones 62/285transfer between the upper and lower shell walls is ob 3.320.764 5/1967Saunders... viated. 3.599.442 8/l97l Hanson..... 3.724.233 4/1973 Pugh62/288 3 Claims, 6 Drawing Figures l l I l l t I 60 a) e r. l V 1 76[Li]: 7% l I .66 t

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PATENTEDMAR 4W5 3,868,829 sum 2 95 3 INSULATION DIVIDER FOR REFRIGERATORCABINET This invention relates to refrigerator cabinet construction andmore particularly to a moisture barrier composite plastic insulation anddrain trough separator located between the freezer and food storagecompartments of the refrigerator.

The prevention of water vapor migrating into rigid plastic foam cellularinsulation dividers for refrigerator cabinets has long been a problem.The fact that moisture adversely affects the performance of insulationis generally known wherein moisture pick-up in the divider insulationcauses resultant frost forming thermo conductive bridges from the warmto the cold side of the insulation. The problem manifests itself asdrops of water or frost on the top wall of the food compartment liner ofthe refrigerator.

It is an object of this invention to provide an insulation divider orseparator between the freezer and fresh food compartments ofa domesticrefrigerator compartment wherein a composite plastic divider includes amolded polyethylene sealed outer shell which is completely filled withunfused pre-expanded polystyrene beads, each of the beads beingsubstantially spherical in shape and having a diameter of the order of0.060 to 0.100 inches whereby the plastic outer shell serves as thevapor barrier such that the expanded polystyrene beads and entrapped airproviding the required insulating medium with the preexpanded unfusedbeaded core serving to obviate the development of air circulationcurrents within the shell which, if permitted, would produce unwantedconvection heat transfer between the upper and lower walls of theseparator.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings wherein a preferred embodiment of the present invention isclearly shown.

In the Drawings:

FIG. 1 is a perspective view of a refrigerator cabinet showing thelocation of the insulation divider of the present invention;

FIG. 2 is a top elevational view of the insulation divider;

FIG. 3 is a back elevational view taken along the lines 3-3 of FIG. 2;

FIG. 4 is a side elevational view taken along the line 4-4 of FIG. 2;

FIG. 5 is a fragmentary side elevational view along line 55 of FIG. l;and

FIG. 6 is an enlarged vertical sectional view taken along the line 6-6of FIG. 2.

Referring now to the drawings and more particularly to FIG. 1, there isshown an insulated household refrigerator cabinet IO'having an outermetal shell 11 with the visible portions including right hand side wall12, top wall 13, bottom wall 14 including an upper offset portion 16which forms the ceiling of the machinery compartment therebelow.

The cabinet is provided with an upper below-freezing compartment 22, anda lower above-freezing or cooling compartment 24, both being enclosedwithin an inner liner preferably formed out of suitable sheet plasticsuch as acrylic butadienc styrene copolymer with the liner side wall 26and rear wall 27 being visible in FIG. I. The space between the innerwalls, formed by the inner liner and the other metal shell 11, is filledwith expanded polyurethane foam which is conventional practree.

The sidewalls 12 and the top Wall 13 are reinforced at the front with aninwardly turned flange 28 extending inwardly substantially at rightangles to the side and top walls around the access opening of thecabinet. Suitable brackets (not shown) extend through openings in flange28 and support a front metal cross member (FIG. 5) extending betweenthem. The details of one such refrigerator cabinet construction areshown, for example, in US. Pat. No. 3,633,374 issued to James A. Canterand assigned to the same assignee as the present application.

As best seen in FIG. 5, the compartments are separated by an insulatedhorizontal partition assembly 30 which includes a lower sheet metal wall32 having a high front portion 34 and a low rear portion 36 with aninclined portion 38 in between. The top member 40 of the partitionassembly is provided with a series of air entrances 42 which connectswith the air passages 44 in the front insulation piece 46 and with theevaporator chamber 48. The evaporator chamber 48 is also surrounded byan insulation piece SU having a passage 52 providing communication withthe air entrance 54 from the above freezing compartment 26 to theevaporator chamber 48.

The evaporator chamber 48 includes an evaporator 56 which is supportedon the drain pan 57. The evaporator is supplied with liquid refrigerantin a manner shown and described in the above-mentioned Canter patent. Afan motor 58 is provided with a front inlet centrifugal fan 60 at therear which draws air through the air inlets 42 and 54 into theevaporator chamber 48 and through the evaporator 56 discharging the airupwardly through the duct 62 into below freezing compartment 22 while areduced amount of air is discharged downwardly through the duct 64 intothe above freezing compartment 26. A light socket 66, provided with alight bulb 68, is controlled by a door switch and plunger 72 toextinguish the bulb 68 when the lower door partially shown at 74, isclosed. A metal trim strip 76 is supported on a front metal cross member29 extending between suitable side wall brackets (not shown).

Defrost heaters 80 melt the frost from the evaporator 56 and the frostwater resulting therefrom flows into the drain pan 57 and its integraldrainage funnel portion 82 formed therein including tubular end orifice83.

Located in the partition space between the upper drain pan 57 and thelower wall 32 is a thermal insulation divider or separator generallyindicated at 84 in the form of a composite plastic panel or articleincluding a molded outer plastic shell or envelope having an upper wall86 and a bottom or lower wall 88, a front outwardly sloping wall 90, arear wall 92, and sidewalls 93 and 94. It will be noted in FIG. 6 thatthe shell bottom wall 88 terminates in an L-shaped flange portion havingupwardly directed flange leg 96 and an outwardly extending flange leg 97which form a flush seal juncture with the peripheral rear edge portion98 of drain base wall 100. The outer shell is preferably formed by blowmolding from suitable plastic material which in the preferred form ispolyethylene plastic having a material thickness of about 0.06 inches.

As best seen in FIG. 2, the shell [upper wall 86 has integrally formedtherein a depressed longitudinally extending rearwardly sloped draintrough defined by the drain trough base 100 and side slopes 102 and 104forwardly converging in a semicircular or arcuate portion 106 having itscenter vertically aligned and concentric with the exit orifice 83 ofdrainage pan funnel 82. Thus, as seen in FIGS. 5 and 6, the melted frostwater collected by the drain pan 57 flows from the funnel 82 to exit viaorifice 83 into the separator drain trough for flow on the base 100 tothe lower rear wall 27 to a drain 110 (FIG. 1) in the bottom wall 14 ofthe cabinet.

As seen in FIGS. 3 and 4, entrance means for the divider shell orenvelope may be provided in the form of an upwardly extending integraltube 112 formed in top wall. By means of the tube 112 the divider shellis completely filled with unfused pre-expanded polystyrene beads,indicated at 114 in FIG. 6, each bead being generally spherical in shapeand having a diameter within the range of about 0.060 to 0.100 inches.The beads 114, which preferably have a density of the order of about 2pounds per cubic foot, after filling the space enclosed by the panelshell are sealed therein and the tubular portion 112 removed from theupper wall 86.

The beads 114 are originally formed from polystyrene spheres which havebeen treated with Freon solvent, either gas or liquid, or alternativelywith a low boiling solvent such as pentane. The spheres, which areoriginally about 0.030 inches in diameter, absorb about 6-8 percent ofthe solvent after which they are expanded unconfined by either dry heator steam injection with the result that the absorbed solvent expands thespheres to their pre-expandecl beaded state.

As seen in FIG. 5, the pre-expanded beads 114 completely fill the sealedair space of the divider shell to provide a plurality of voids occupiedby the entrapped air, which beads and air thus form the core materialfor the insulation divider 84. A function of the contacting beads is toprevent the formation of circulating convection air currents within themoisture impervious sealed plastic divider shell which would result fromthe temperature differential between the shell top wall 86, exposed tofreezer compartment temperature ranging from about 2 to +15F. and theshell bottom wall 88 exposed to the above freezing food storagecompartment temperatures ranging from about 34 to 40F.

It will be noted in FIGS. 5 and 6 that the arcuate sloped portion 106 ofthe divider top wall is molded to conform with the funnel portion 82 ofthe drain pan while inner inclined arcuate notch 120 encloses about l80of the downwardly extending circular lip portion of the funnel 82. Inthis way only the drain base 100 and the adjacent drain side steepslopes 122 and 124 extending between the base 100 and the reduced slopes102 and 104 are open to allow defrost water to drain to the refrigeratorrear wall.

As the defrost heaters 80 are of the infra-red emitting type, certainportions of the drain base 100 and steep slopes 122 and 124 are exposedto the infra-red rays which rays would melt and destroy the portions ofthe plastic shell exposed to the rays. To obviate this from occurring analuminum foil strip or tape 126 is affixed to the upper surface of thedrain base 100 and the steep side slopes 122 and 124 to reflect theinfrared rays and protect the underlying plastic material therefrom.

It will thus be seen that applicants have invented an improvedinsulation separator panel for refrigerators whereby the panel upper andlower walls are molded to conform to and contiguous with the overlyingdrain pan and the underlying supporting wall, respectively to form amoisture impervious airtight insulator for a refrigerator cabinet withthe sealed cavity being filled with the beads 114 whereby static airtherein is confined in the air spaces between the beads to minimizeconvection heat transfer between the upper and lower walls of theseparator shell.

While the embodiment of the present invention as herein disclosedconstitutes a preferred form, it is to be understood that other formsmight be adopted.

We claim:

1. A refrigerator including a cabinet having insulated walls enclosing acompartment, a laterally extending dividing means within saidcompartment dividing said compartment into an upper freezer compartmentand a lower fresh food compartment, door means for closing saidcompartments, said dividing means including a bottom supporting wall, adrain pan spaced above said supporting wall for supporting an evaporatorthereon, wherein the improvement comprises an insulation separator onsaid supporting wall, said separator comprising an outer molded moistureimpervious plastic shell having upper, bottom, front, rear and sidewalls forming an air-tight sealed chamber, said shell upper and bottomwalls substantially conforming to and contiguous with said drain pan andsaid supporting wall, respectively; said sealed chamber completelyfilled with unfused, pre-expanded polystyrene contacting beads; each ofsaid beads being substantially spherical in shape and having a diameterof about 0.060 to 0.100 inches, said beads forming a plurality of airspaces therebetween so that static air is confined in the air spaceswhereby convection heat transfer between the upper and lower walls ofsaid separator shell is obviated.

2. A refrigerator including a cabinet having insulated walls enclosing acompartment, a laterally extending dividing means within saidcompartment dividing said compartment into an upper freezer compartmentand a lower fresh food compartment, door means for closing saidcompartments, said dividing means including a bottom supporting wall, adrain pan spaced above said supporting wall for supporting an evaporatorthereon, said drain pan including an integral frustoconical drainagefunnel formed therein having an exit orifice, wherein the improvementcomprises; a composite insulation separator and drain trough supportedon said bottom supporting wall, said separator comprising an outermolded plastic shell having upper, bottom, front, rear and side wallsforming a sealed chamber, recess means molded in said upper wall surfacefor conducting drainage water from said funnel to a wall of saidcabinet, said chamber being completely filled with unfused, pre-expandedpolystyrene contacting beads, said beads being substantially sphericalin shape and having a diameter within the range of about 0.060 to 0.100inches, and a density of the order of two pounds per cubic foot; saidbeads forming a plurality of air spaces therebetween so that static airis confined in the spaces whereby convection heat transfer between saidupper and lower walls of said separator shell is obviated.

3. A refrigerator including a cabinet having insulated top, bottom, rearand side walls enclosing a compartment; a laterally extending dividingmeans within said compartment dividing said compartment into an upperfreezer compartment and a lower fresh food compartment, door means forclosing said compartments, said dividing means including a bottom sheetmetal wall having a high front portion and a low rear portion with aninclined connecting portion in between, a drain pan spaced above saidsheet metal wall low rear portion for supporting an evaporator thereon,said drain pan including an integral frusto-conical drainage funnelformed therein having an exit orifice, wherein the improvementcomprises; a composite insulation separator and drain trough supportedon said sheet metal wall low rear portion, said separator comprising anouter molded shell of polyethylene plastic material having upper,bottom, front, rear and side walls forming a sealed chamber; said sealedchamber completely filled with unfused, pre-expanded polystyrenecontacting beads having a substantially spherical shape and having adiameter within the range of about 0.060 to 0.100 inches, said beadsforming a plurality of air spaces therebetween so that static air insaid chamber is confined in the spaces whereby convection heat transferbetween the upper and lower walls of said separator shell is obviated,and said separator upper wall surface having a plurality of inwardlysloping walls defining a recess extending longitudinally from the rearwall of said separator and terminating adjacent the center of said uppersurface in an arcuate portion conforming with said frusto-conicaldrainage funnel, the base of said recess being sloped toward saidseparator rear wall for directing the flow of drainage water from saiddrainage funnel to said refrigerator cabinet rear wall.

1. A refrigerator including a cabinet having insulated walls enclosing acompartment, a laterally extending dividing means within saidcompartment dividing said compartment into an upper freezer compartmentand a lower fresh food compartment, door means for closing saidcompartments, said dividing means including a bottom supporting wall, adrain pan spaced above said supporting wall for supporting an evaporatorthereon, wherein the improvement comprises an insulation separator onsaid supporting wall, said separator comprising an outer molded moistureimpervious plastic shell having upper, bottom, front, rear and sidewalls forming an air-tight sealed chamber, said shell upper and bottomwalls substantially conforming to and contiguous with said drain pan andsaid supporting wall, respectively; said sealed chamber completelyfilled with unfused, pre-expanded polystyrene contacting beads; each ofsaid beads being substantially spherical in shape and having a diameterof about 0.060 to 0.100 inches, said beads forming a plurality of airspaces therebetween so that static air is confined in the air spaceswhereby convection heat transfer between the upper and lower walls ofsaid separator shell is obviated.
 2. A refrigerator including a cabinethaving insulated walls enclosing a compartment, a laterally extendingdividing means within said compartment dividing said compartment into anupper freezer compartment and a lower fresh food compartment, door meansfor closing said compartments, said dividing means including a bottomsupporting wall, a drain pan spaced above said supporting wall forsupporting an evaporator thereon, said drain pan including an integralfrusto-conical drainage funnel formed therein having an exit orifice,wherein the improvement comprises; a composite insulation separator anddrain trough supported on said bottom supporting wall, said separatorcomprising an outer molded plastic shell having upper, bottom, front,rear and side walls forming a sealed chamber, recess means molded insaid upper wall surface for conducting drainage water from said funnelto a wall of said cabinet, said chamber being completely filled withunfused, pre-expanded polystyrene contacting beads, said beads beingsubstantially spherical in shape and having a diameter within the rangeof about 0.060 to 0.100 inches, and a density of the order of two poundsper cubic foot; said beads forming a plurality of air spacestherebetween so that static air is confined in the spaces wherebyconvection heat transfer between said upper and lower walls of saidseparator shell is obviated.
 3. A refrigerator including a cabinethaving insulated top, bottom, rear and side walls enclosing acompartment; a laterally extending dividing means within saidcompartment dividing said compartment into an upper freezer compartmentand a lower fresh food compartment, door means for closing saidcompartments, said dividing means including a bottom sheet metal wallhaving a high front portion and a low rear portion with an inclinedconnecting portion in between, a drain pan spaced above said sheet metalwall low rear portion for supporting an evaporator thereon, said drainpan including an integral frusto-conical drainage funnel formed thereinhaving an exit orifice, wherein the improvement comprises; a compositeinsulation separator and drain trough supported on said sheet metal walllow rear portion, said separator comprising an outer molded shell ofpolyethylene plastic material having upper, bottom, front, rear and sidewalls forming a sealed chamber; said sealed chamber completely filledwith unfused, pre-expanded polystyrene contacting beads having asubstantially spherical shape and having a diameter within the range ofabout 0.060 to 0.100 inches, said beads forming a plurality of airspaces therebetween so that static air in said chamber is confined inthe spaces whereby convection heat transfer between the upper and lowerwalls of said separator shell is obviated, and said seParator upper wallsurface having a plurality of inwardly sloping walls defining a recessextending longitudinally from the rear wall of said separator andterminating adjacent the center of said upper surface in an arcuateportion conforming with said frusto-conical drainage funnel, the base ofsaid recess being sloped toward said separator rear wall for directingthe flow of drainage water from said drainage funnel to saidrefrigerator cabinet rear wall.